Humus or Compost?

Veronika Bond Humus

“HOMO – HUMUS – HUMANITAS, three words, the same origin, the same destiny.”Friedensreich Hundertwasser

Do you know the difference between humus and compost?

I used to think the difference is pretty obvious. However, since this has become one of my favourite topics to read, write and talk about, I realised that it’s not that obvious at all!

In popular English gardening literature the words are often used interchangeably. In German gardening books, the difference is usually pretty clear, although in blogs and online conversations it is not necessarily so.

Because there is obviously some confusion about compost and humus, I did a little experiment. For our recent ‘mini composting workshop’ (April 5th) I prepared two jars, one with compost and one with humus. Which one is which?

There were about 20 people at the workshop. Some labelled the brown jar as ‘Humus’ and the colourful one as ‘Compost’. Others thought the left one was ‘Compost’, and then there was some hesitation about the right one.

I’m a linguist, and I like to research the origins of words. I love language because it is such a rich source of knowledge. Words themselves often ‘know what they are’. Here are some snippets from my research:

The word humus is Latin, and originally it meant earth. The word human comes from the same root, and so does the first part of the word homogenous. Homos is a Greek word and means like. And human literally means ‘the earthly one’.

When the word humus was introduced into the European languages in the 19th century, it was used in the sense of the brown stuff you can see in the jar on the left. The German agronomist Albrecht Thaer, the Austrian philosopher Rudolf Steiner, the Ukrainian microbiologist Selman Waksman, the English farmer Sir Albert Howard, Lady Eve Balfour, founder of the British Soil Association, they all used the word humus in this sense.

So how did the confusion between compost and humus happen?

Fortunately, one expert gardener and co-organiser of our composting day had the answer:

It’s because you can buy the brown stuff in bags in the garden centre, and it’s got COMPOST written on it!

The word compost also comes from Latin, and it literally means something put together. This is what you can see in the jar on the right. Compost is a composition of different kinds of organic stuff which will eventually decompose and become humus.

Humus is a homogenous entity. You could say, it is ‘mature compost’ in its transformed state.

On the other hand, the difference between compost and humus is quite significant. It is actually as phenomenal as the difference between a caterpillar and a butterfly.

But now back to the stuff in my two jars. My Humus-jar contains mature humus from a 10 year old pile. My Compost-jar contains the following layers:

  • Very small sticks at the bottom
  • Some nettles and other green wild plants chopped
  • A thin layer of humus
  • Some sand
  • More green plant materials (chopped comfrey leaves) and yellow flowers (mustard and kale)
  • A bit more humus
  • A broken up egg box on top

After one week (April 12th) there was no change in my ‘Compost-jar’ (the one with the colourful composition in it). Then I decided to sprinkle some ‘compost activator’ over the top, and two weeks later the jars look like this:

The humus in the jar on the left is unchanged, and the compost in the jar on the right is now well on its way to turn into humus. Some liquid has drained to the bottom, the sticks are still visible, the whole composition has sunk down by about one quarter. The sticks at the bottom and egg box pieces at the top have not yet decomposed, but the layers in between are beginning to look homogenous.


The humus revolution has begun — you can be part of it